In the packaging industry, plastic bags can be manufactured by continuously extruding plastic formed in a tube and then cutting the tube to length forming a bag. The bags are folded and then packaged in cardboard containers or cartons. A predetermined number of bags are placed in the carton for final packaging.
Problems exist in the packaging of bags produced by a continuous process. The bags continue to be ejected from the manufacturing machine at a constant rate. However, the time between bags is greatly less than the time required to move a full box of bags and insert a new box for catching the continuous flow of bags. This problem becomes acute in an automated production with a high rate of manufacture.
Several devices have been proposed. One such device utilizes a pair of plates which operate like bomb doors. The plates are held in a horizontal position to catch the bags being ejected from the bag manufacturing apparatus while the filled box is being moved along to make room for an empty box. Once the empty box is in place, the plates open like bomb doors dropping the load of accumulated plastic bags into the box. The plates are closed re-establishing a surface for catching the flow of plastic bags.
The problem with this type of apparatus is that the opening and closing of the plates cannot be accomplished quickly enough to cleanly stop the flow of plastic bags. As the plates close, there is a high risk that a number of plastic bags being ejected will get caught between the closing plates. This results in jamming of the apparatus. This problem limits the rate of production preventing significant increases in production speed.
In another type of apparatus, as described in U.S. Pat. No. 4,043,458, a fence is used to stop the forwardly projected bag. Once a desired number of bags have been stopped, the fence is raised to permit the completed stack to move forward along a conveyor while the fence continues to stop the forwardly projected bags forming the next-to-be-completed stack.
The problem with this type of apparatus is that the bags must be stacked on the conveyor. The bags cannot be directly loaded into a carton for final packaging. Loading into a carton requires a separate apparatus for loading the stacks of bags.